Estimation of Aortic Stiffness with Bramwell–Hill Equation: A Comparative Analysis with Carotid–Femoral Pulse Wave Velocity

Figures

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  Figure 1. Experimental data from two subjects with different carotid–femoral pulse wave velocities (cf-PWV): (A,B) subject with medium PWV; (C,D) subject with high PWV. Ultrasound scans are considered in (A,C), showing two frames corresponding to local minimum and maximum average diameter (left) and the diameter over time (right). The indication of average pulsatility ΔA/A and pressure variation (ΔP, obtained using PulsePen in these cases) are provided. Tonometry is shown in (B,D), for both the carotid and femoral artery, with the measured cf-PWV indication.

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  Figure 2. Experimental measurements, including repetitions for specific subjects: carotid–femoral pulse wave velocity (cf-PWV); pulsatility (ΔA/A), indicated as the ratio between the range and the mean value of the area of the aorta measured by automated edge tracking from ultrasound scans; and pressure variation using either PulsePen or SphygmoCor (ΔP).

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  Figure 3. Comparison of PWV measured estimated by the Bramwell–Hill equation using the measurements of pulsatility and pressure variation (correlation coefficient 17.8%). Scatter plot (left) and Bland–Altman representation (right).

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  Figure 4. Comparison of measured and estimatedpulsatility by inverting Bramwell–Hill equation and using the measurements of PWV and pressure variation (correlation coefficient 56.1%). Scatter plot (left) and Bland–Altman representation (right).

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  Figure 5. Comparison of pressure variation either measured or estimated by inverting Bramwell-Hill equation and using the measurements of PWV and pulsatility (correlation coefficient 54.5%). Scatter plot (left) and Bland-Altman representation (right).

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  Figure 6. Sensitivity of PWV estimated by Bramwell–Hill equation to certain variables: blood density, error in measuring pulsatility, error in the estimation of pressure variation.